Field of the Invention
The present invention relates to an image forming apparatus, an image forming apparatus control method, an image processing apparatus, an image processing method and a storage medium.
Description of the Related Art
There is known an electrophotographic image forming apparatus that forms a toner image on a print medium, and thermally fixes the formed toner image to the print medium. Typically, such an image forming apparatus decides the amount of toner to deposit on the print medium (hereinafter designated the “toner amount”) for each pixel of image data, based on image data that has undergone a color separation process (raster image data). For example, if the minimum value and the maximum value of the component value of a color in a certain pixel (hereinafter designated the “color component value”) corresponds to the 8-bit values of 0 and 255, a color component value of “0” indicates a toner amount of 0%, while a color component value of “255” indicates a toner amount of 100%.
A multicolor image forming apparatus decides the toner amount based on the color component values for respective colors, such as CMYK (cyan, magenta, yellow, black). For this reason, if the color component values for a certain pixel are (C, M, Y, K)=(255, 255, 0, 0), for example, the toner amount for that pixel becomes 100%+100%+0%+0%=200%. In this way, a multicolor image forming apparatus tends to deposit a greater amount of toner on the print medium than a monochrome image forming apparatus.
If the amount of deposited toner becomes excessive, toner fixing failure may occur in some cases. For example, excess toner may melt during fixing and peel off from the print medium, or the print medium may wrap around the fixing roller. Image forming apparatuses that conduct toner amount control to prevent toner fixing failure are widely known. Such an image forming apparatus controls the reduction of the amount of toner to a limiting value on the toner amount to use for image formation. Furthermore, a technology that decides the limiting value according to a temperature setting for the fixing device which consumes a large amount of electric power, and controls the amount of toner to be less than or equal to the decided limiting value has also been proposed (Japanese Patent Laid-Open No. 2014-092679).